The creature knocked Lillian Peterson off her feet as she was climbing out of Lake Barcroft after a swim. The 83-year-old woman twisted around to see what attacked her and noticed one thing: large, orange teeth.

A 35-pound, 24-inch rabid beaver had bitten her on the back of the leg and would not let go, sparking an ordeal that lasted more than 20 minutes Tuesday evening. The Falls Church woman and a friend battled the animal with canoe paddles, a stick and bare hands as it came at them again and again. Peterson was seriously injured.

Authorities said such attacks are exceedingly rare in suburban Washington; it was the first in Fairfax County in at least 12 years.

“It bit me so bad,” Peterson said during a phone call from her bed at Inova Fairfax Hospital, where she was recovering. “I started kicking it with my other leg, but I wasn’t sure what I would do.”

The evening had started very differently. As she did on many nights, Peterson went for a swim in the 135-acre private lake in the Baileys Crossroads area of Fairfax. Peterson is athletic and active, still swimming and working as a real estate agent.

Lillian Peterson is hospitalized after a rabid beaver attacked her.

A co-worker at Long & Foster, Mike Korin, also happened to be at the lake that night, giving a fishing lesson — a coincidence that would help free Peterson from the attack.

About 6 p.m., Korin noticed the beaver splashing around the lake. It struck the avid fisherman and former U.S. Forest Service employee as unusual. Soon, he said, he saw it swimming toward Peterson, who was just finishing up her swim on a far bank.

Then Peterson went down.

“I heard horrible yelling and knew it was the real deal,” Korin said. “She was saying, ‘I can’t get out of its grip. It’s got me.’ ”

Korin fired up the engines on his boat and began heading across the lake. He also dialed 911.

Peterson, who has been a top real estate agent for Long & Foster, said she immediately began fighting back. She grabbed for a walking stick and gouged the beaver in its eyes, thinking she could blind it, she said.

During the struggle, the beaver took a bite out of her left calf, nearly bit off her thumb, and left puncture wounds all over her arms and legs, Korin and Peterson said. Still, it wouldn’t stop.

By the time Korin got to Peterson, he said, he had a Fairfax emergency dispatcher on speakerphone but had a difficult choice to make: Explain the situation to authorities, give Peterson medical aid or try to neutralize the beaver.

Suddenly, the animal let go of Peterson and swam directly at Korin’s boat — its only route of escape, he said. Korin said he picked up a canoe paddle and “started beating savagely” on the beaver, breaking the paddle in the process.

Korin said the attack seemed to stun the animal, so he turned his attention to helping Peterson get out of the water and dealing with the emergency dispatcher. But as he was lifting Peterson on the bank, the beaver came at them again. He said he had to beat it back with the paddle one more time. Then it seemed dead.

An emergency medical crew arrived shortly after and began treating Peterson. The ordeal appeared to be over. But the relief was short-lived.

“All of a sudden, the beaver flips over and comes back to life,” Korin said.

One of the paramedics grabbed another canoe paddle to beat the animal a third time, Korin said. Korin jumped in and out of his boat, trying to corral the beaver because he did not want it to get away and attack someone else, he said.

Finally, he was able to toss a net over its head and trap it. He lashed the bagged animal to a light pole on the lake shore. When animal control officers arrived, they euthanized the beaver.

Korin said Peterson was so tough that she was chatting up the paramedics as she was being put in the ambulance. She was taken to the hospital, where she was expected to remain Wednesday night.

Peterson said she was being treated for rabies with painful shots after Fairfax police said the beaver tested positive for the virus. Officers planned to hand out fliers in the neighborhood explaining the dangers of rabies.

Authorities said an animal’s strange behavior is often a sign that it has rabies. People should keep their distance and report animals that are sick or threatening to the Animal Services Division of Fairfax’s police department.

Lake Barcroft is a popular recreation spot for boaters, swimmers and fishermen. Sally Determan, the Lake Barcroft Association president, said that a biologist estimated there were 12 to 15 beavers living on the lake but that they had never attacked a person before in the four decades she has lived in the area. The association has advised residents not to swim in the lake for now.

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